Various devices and methods have been traditionally used to combat a physical condition known as Barrett's esophagus. Barrett's esophagus is the abnormal growth of intestinal type cells into the esophagus resulting from stomach acid chronically refluxing into the esophagus. Most people occasionally experience heartburn, which is the refluxing of stomach acid beyond the lower esophageal sphincter muscle and into the esophagus. Such occasional heartburn is not harmful. Severe or frequent reflux, however, is harmful and known by the names gastroesophageal reflux disease (GERD) and chronic reflux esophagitis (also known as Chronic Acid Reflux, or CAR). About one out of every ten patients with GERD/CAR are found to have Barrett's esophagus. In patients with Barrett's esophagus, the healthy mucosal cells of the inner layer or the squamous epithelium of the esophagus are replaced with diseased or intestinal cells. It is believed that such growth is a defense mechanism of the body to avoid esophageal injury due to the acid refluxed from the stomach. Unfortunately, these mucosal tissue changes may lead to low, then high grade dysplasia, and eventually to cancer of the lower esophagus, known as adenocarcinoma.
A common method for destroying diseased esophageal tissue has been to cauterize or coagulate the unwanted tissue with a conventional ablation device. Ablation devices have developed as an alternative to other traditional means for eliminating unwanted tissue, such as cutting away the tissue, cryotherapy, and thermal therapy. Cryotherapy is the application of extreme cold to freeze and destroy diseased mucosal tissue. Thermal therapy is the application of heat to coagulate, cauterize and/or ablate diseased mucosal tissue. Sufficient raising or lowering of tissue temperature causes necrosis of the tissue. For convenience, the term ablate will be used herein to describe any and all of these thermal therapy processes. In use, these devices are placed adjacent the unwanted tissue and tissue is ablated, cauterized, coagulated, frozen, or burnt, as the case may be, by energy transmitted from or to the device.
Traditional ablation devices have two primary shortcomings. First, traditional devices can ablate only relatively small portions of patient tissue at one time. For example, ablation devices having a surface for ablating patient tissue by transmitting energy to or from the device can only ablate an area of patient tissue substantially equal to the area of the transmission surface in a single energy transmission. Further, traditional ablation devices can only ablate one side of an esophagus at any one time.
A second primary shortcoming of traditional ablation devices is their inaccuracy in use. A primary challenge for battling Barrett's esophagus is to destroy targeted tissue without affecting healthy adjacent esophageal cells or muscular cells underlying the diseased and healthy tissue. Injury to the healthy underlying muscular tissue, for example, can lead to the creation of a stricture or constriction in the esophagus. Many traditional ablation devices ablate targeted tissue without first isolating the targeted tissue from the adjacent and underlying healthy tissue. As a result, when too much energy is transferred to or from the device, ablation of healthy adjacent cells and/or underlying muscular cells can occur. On the other hand, when too little energy is transferred from the device, less than all of the targeted tissue is ablated.
The conventional approaches for treating Barrett's esophagus or other diseases requiring the precise ablation of relatively large areas of intralumenal tissue are insufficient in these regards. Thus, there is a need for an ablation device and method for using such a device that allow accurate and minimally invasive ablation of relatively large amounts of intralumenal patient tissue.